Israel believes Syria has retained caches of combat-ready chemical weapons after giving up raw materials used to produce such munitions, a senior Israeli official told Reuters on Thursday.
The official said Israel believe the Syrians have kept some missile warheads, air-dropped bombs and rocket-propelled grenades primed with toxins like sarin.
"There is, to my mind, still in the hands of Syria a significant residual capability ... that could be used in certain circumstances and could be potentially very serious," the official told Reuters on condition of anonymity.
While saying Israel had a "high degree of confidence" in its information, he declined to give figures for chemical weapons allegedly kept by Syria.
"What we are saying is that there are a number of questions here that still have to be clarified, still have to be looked at very closely" by international inspectors, the official told Reuters.
Syria signed up to an international plan to destroy its chemical stockpile after the outcry that followed chemical attacks by the Damascus regime in August last year that may have killed as many as 1,400 people.
U.S. President Barack Obama recently announced that Syria's declared chemical weapons stockpile was eliminated, declaring this an important achievement against the spread of dangerous weapons of mass destruction.
The Israeli official told Reuters that the 1,300 tons of mustard gas and precursors for sarin and VX surrendered by Syria largely matched Israeli assessments of its total stockpile of such materials. The shelf-life of any deployable munitions held back was limited given the chemicals' deterioration, he added.
Those assessments appear to contribute to overall Israeli relief at the Syrian chemical disarmament, even if President Bashar Al-Assad has reneged in part. The Israeli official voiced confidence that "our deterrence" - usually a coded reference to Israel's superior military and assumed nuclear arsenal - would continue to keep Damascus in check.
Using chemical weapons against Israeli targets, even on a small scale, "wouldn't be a game-changer, it would be a game-ender" for Syria, the official said.